(a) Technical Field
The present invention relates to a fuel cell vehicle. More particularly, it relates to a fuel cell vehicle equipped with a moisture remover that can remove moisture from an air conditioner evaporator.
(b) Background Art
A fuel cell is a type of electric generator which directly converts chemical energy of fuel into electric energy.
PEMFCs (Polymer Electrolyte Membrane Fuel Cell) are fuel cells that demonstrate high efficiency, large current density and output density, short start time, and rapid response to a change against a load, and, thus, are widely used for vehicles.
In order to use a fuel cell for the power unit of a vehicle, a stack is formed by stacking unit cells of fuel cells to achieve desired power. Various operation devices are then added to form the power unit, and the unit is mounted in the vehicle.
The operation devices of the fuel cell include a hydrogen supply device, an air supply device, and a heat and water management system. The hydrogen supply device supplies hydrogen as fuel to the stack. The air supply device supplies air containing oxygen as an oxidizer to the stack. The heat and water management system optimally manages the operation temperature of the stack by externally discharging heat, which is a byproduct of electrochemical reaction in the stack, and manages water.
The hydrogen supply device includes a hydrogen tank, a hydrogen supply valve, a compressor adjuster, and a hydrogen recirculator (recirculating blower and ejector). The air supplier includes an air supplier (air blower), an air valve, and a humidifier. The heat and water management system includes a cooling water pump, a radiator, a 3-way valve, and a water discharger for discharging water from the stack.
Further, a hydrogen purge valve is provided in a hydrogen exhaust line for removing impurities from an anode, and a cathode oxygen depletion is provided for removing stack voltage.
The cathode oxygen depletion is described in more detail as follows. When a fuel cell vehicle is stopped and the system is shutdown by Key-off/IG-off, hydrogen and oxygen are exchanged through the electrolyte membrane and deterioration of the catalyst layer is accelerated. Further, when the stack voltage is higher than the predetermined voltage, hydrogen and oxygen remain at the anode and the cathode, respectively.
Therefore, when shutting down the system, it is essential to reduce the stack voltage so as to remove the hydrogen and oxygen from the anode and the cathode. One conventional method is to reduce the stack voltage while reducing the oxygen remaining in the cathode by connecting a COD (Cathode Oxygen Depletion) to the stack.
The COD removes the oxygen and voltage remaining in the cathode of the stack by reacting the oxygen remaining in the stack with the hydrogen for each shutdown, thereby discharging the electricity into heat
Similar to conventional engine vehicles, a fuel cell vehicle is equipped with an air-conditioning system to control the interior temperature. Unlike conventional engine vehicles which use hot cooling water of the engine to heat the vehicle interior, fuel cells use an electric heater to heat the interior. A PTC (Positive Temperature Coefficient) heater is commonly used as the electric heater.
A fuel cell vehicle is further equipped with a liquid coolant type of air conditioner, which comprises an evaporator, a compressor, a condenser, and a throttle valve, similar to conventional engine vehicles. However, unlike conventional engine vehicles, fuel cell vehicles cannot utilize driving force from the engine to operate a compressor. Instead, an electric compressor using torque of a motor is used.
However, during operation of the air conditioner, a large amount of water condenses on the core surface of the evaporator. Further, even when the air conditioner is turned off, water condenses from the cold air on or around the core surface of the evaporator, which is in contacts with the external hot air. Therefore, although water is discharged through a drain hose of an air-conditioning duct, water that condenses on the core of the evaporator is not completely discharged through the drain hose and, thus, remains therein. As a result, when external dust and pollen enters the interior while water remains in the evaporator, molds form and proliferate, which results in the generation of a bad and unpleasant odor during the early operation of an air conditioner.
FIG. 1 shows an example of the configuration of an air-conditioning system provided in a common fuel cell vehicle. As shown, the system includes which an air-conditioning heater (PTC heater) 30, a blower fan 31, an air-conditioning duct 33, an air conditioner (evaporator) 51, a compressor 52, a condenser 53, a throttle valve 54, a stack 10 that is the main power supplier of the fuel cell vehicle, and a COD 20 that removes oxygen remaining in the cathode of the stack 10 in shutdown.
Looking to FIG. 1, when a switch 32 is turned on, the electric heater 30 is operated by power from the stack 10. As external air or internal air pass through the electric heater 30 by means of the blower fan 31, it becomes heated. The heated air is then supplied to the inside of the vehicle through the air-conditioning duct 33.
Further, when the fuel cell system is shut down, the COD 20 is connected to the stack 10 by turning on the switch 21, such that oxygen in the cathode of the stack and the remaining voltage are removed.
However, the electric heater 30 of the fuel cell vehicle is used only as a heater for heating the interior, such as in the winter, and the air conditioner evaporator 51 is not equipped with any device for removing moisture.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.